This invention relates to the forging of gamma titanium aluminide alloys.
Titanium alloy parts are ideally suited for advanced aerospace systems because of their excellent general corrosion resistance and their unique high specific strength (strength-to-density ratio) at room temperature and at moderately elevated temperatures. Despite these attractive features, the use of titanium alloys in engines and airframes is often limited by cost due, at least in part, to the difficulty associated with forging and machining titanium.
Recent developments in advanced hypersonic aircraft and propulsion systems require high temperature, low density materials which allow higher strength to weight ratio performance at higher temperatures. As a result, titanium aluminide alloys are now being targeted for many such applications. Titanium aluminide alloys based on the ordered gamma TiAl phase are currently considered to be one of the most promising group of alloys for this purpose. These alloys are lightweight, yet resistant to oxidation and deformation at temperatures as high as 1800.degree. F. (1000.degree. C.). However, the TiAl ordered phase is very brittle at lower temperatures and has low resistance to cracking under cyclic thermal conditions. For the same reasons that these alloys are resistant to high temperature deformation, they are also very difficult to hot work, as by forging, and as a result, it is difficult to manufacture complex shape high quality components.
Accordingly, it is an object of the present invention to provide an improved process for hot working gamma titanium aluminide alloys.
Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art after reading the detailed description of the invention as well as the appended claims.